Cartridges or containers of exothermic welding material are normally plastic containers such as shown in prior U.S. Pat. No. 2,997,165. The contents of the container including the igniting material on the bottom are then emptied into a crucible of a graphite mold leaving the ignition material on top which can then be ignited by a flint gun, for example. The cartridges and molds noted are sold under the trademark CADWELD by Erico Products, Inc. of Solon, Ohio. Such cartridges require some manipulative steps in the field. Moreover, the exothermic process produces a slag which rises to the top of the molten metal formed. Since the molds are normally reused, the slag must be cleaned and removed. This in turn reduces the number of times the mold can be used.
For small quantities of exothermic materials, disposable ceramic molds have been employed with the cartridge such as shown in the above-noted patent actually shipped in the mold. Such molds are illustrated in U.S. Pat. No. 3,020,608 and are also sold under the trademark ONE SHOT by Erico Products, Inc. of Solon, Ohio. Nevertheless, the cartridge of material has to be removed from the crucible chamber of the mold, opened, and emptied into such chamber. In no sense does the cartridge of exothermic material remain sealed or contained until ignition.
In the copending application of Michael D. Amos, David P. Kovarik and George F. Kub, Jr. entitled "Exothermic Welding and Method", filed even date herewith, there is illustrated an ignition system for exothermic materials which does not require the use of low ignition starting materials and which uses a high energy spark aross a spark gap embedded in such exothermic material to obtain ignition. The spark is obtained from a power source using a capacitor discharge circuit. The present invention provides a sealed self-contained package using spark gap ignition providing economies of manufacture, distribution and use, and not requiring the material to be exposed prior to use. Moreover, the manner of use of the cartridge provides more reliable quality welds and increases the economic life of the molds employed.